Method of forming a propeller



ug. 2, 1932'. s, HEATH 1,869,478

METHOD 0F FORMING A PROPELLER Filed Aug. 13, 1930 aucuns,

Patented Aug. 2, 1932 vrara SPENCER HEATH, OFELKRIDGE, MARYLAND, ASSIGNOB TO THE AMERICAN PBOPELLER COMPANY., F BALTIMORE, MARYLAND, A COBBORATIGN QF MARYLAND METHOD 0F FORMING A PROSPELLER Application led August 13, 1930. Serial No. 475,058.

f a novel series of steps for successively shaping the blank into a seamless propeller blade. A still further object is to provide a method of construction which may be executed in a simple and ecient manner for producing a' light, hollow propeller blade having maximum durability.

rlhe above and other objects will appear more fully hereinafter from the following detailed description when vtaken in connection with the accompanying drawing. lt iS to be expressly understood, however, that the drawing is for purposes of illustration only and is not designed as a denition of the limits et the invention, reference being had for this purpose to the appended claims.

ln the drawing, wherein similar reference characters refer to like parts throughout the several views Fig. lis a longitudinal section of a hollow metallic billet or cupped disk suitable for Eorming a blank employed in making a propeller blade in accordance with the present invention;

2 is a view similar 'to l illustratinv' a slightly elongated condition of the billet or cupped dlsk;

Fig. 3 is a longatudinal section of a blade blank after further treatment oit the member oltFig. 2;

r ig.

e illustrates a series o transverse sections taken at suitable intervals through the blank of Fig. 3;

Fig. 5 is a plan view partly in section of the blank after alteration of its perimetrical dimensions,

Fig. 6 illustrates a plurality of .transverse sections through the blank shown in Fig. 5;

Fig. 7 is a plan view partly in section of the completed blade; and

Fig. 8 illustrates a plurality of transverse sections through the completed blade.

In the novel method constituting the present invention, a suitable cupped hollow metal member is employed, which member after suitable manipulation is formed into a hollow tube or blank, closed at one end, and substantially cylindrical except that portion of the blank adjacent the closed end, which is shaped in the form of a wedge. rll`he blank is thereafter treated, in any suitable manner, to decrease the thickness of the wall thereof, from the inner end toward the outer, as illustrated, and suitable internal and external pressures employed to vary the circumferential dimensions to conform substantially with those of the blade to be formed. The resultant blank is then pressed into the desired blade shape having the axial twist characteristic of propeller blades and suitable anges are thereafter termed on the root end of the blade for engagement with correspondingly formed recesses in a suitable hub member.

Referring now to the drawing and more particularly to Figs. l and 2 thereof, there is disclosed therein a hollow metallic cupped disk or billet 9 which may, according to the present invention, be formed by a `:cries of steps, set forth more particularly hereinafter, into a hollow metal propeller blade characterized by the total absence of any joints, welds or seams of any type.

As shown, Fig. l, the metallic member 9 is provided with a flange l0, the purpose of which will appear hereafter. The member 9 after a suitable drawing or rolling process. an

intermediate stage thereof, bein illustrated in Fig. 2, isformed into a blan 11, Fig. 3. The exterior surface of the blank, thus formed, is substantially cylindrical as indicated by the transverse sections 12, Fig. 4. However, the closed end of the blade is substantially wedge-sha ed, asindicated at 13 and 14, such shape eing imparted to the blade end by a suitably shaped die tool durin the elon ation of the member 9 and is e ective to acilitate the subsequent expansion and flattening of the blank into the finished blade.

As illustrated in Fig. 2, the thickness of the Wall of member 9 gradually decreases from the open or inner end toward the closed or outer end, such variation in wall thickness being preferably secured during the drawing or rollin of the member 9 to form the blade blank. f desired, however, the blank 11 may be formed with a wall of uniform thickness durin the elongation of member 9, and the wall t ickness thereafter varied, prior to the flattening of the end of the blank into the form of a wedge, by a machining process.

In order to provlde for the necessary bladel width, the blank 11 is thereafter expanded as shown at 15, Fig. 5, in an suitable manner, it being pointed out that uring this step, the circumferential dimensions of the blade are altered to conform substantially with those of the blade to be' formed. Preferably, to effect such ex ansion, the blank 11 is placed within a suita le mold or two-part die which may be interiorly shaped as indicated by the sections 16, Fig. 6, and sufficient pressure, such as for example, fluid pressure, introduced within the blank to expand the walls thereof to conform to the shape of the mold or die, thereby formin a paddle-shaped member 15. As shown, ig. 6, the above exansi'on step, transforms the sections 12, 14,

4, into sections 16 which are substani tiaIly elliptical, it being pointed out that the subsequent formation of the finished blade is eatly facilitated by such elliptical sections. t is also pointed out, that the perimetrical dim'ensions of the sections 16 approximate corres onding sections of the blade to be formed, although in certain instances the dimensions of sections 16may be greater or less than the blade sections, if desired.

In order to transform the blank .15, thus formed, into a finished blade 17, as illustrated axially twisted in order to efi'ect the proper pitch or angularity in the finished blade 17.

During this last mentioned step, it is contemplated that the internal pressure employed. need be sucient only to prevent Wrinkling or collapse of the blank. However, in certain instances this pressure may be increased, if desired, to effect a further expansion of the blank.

In order to form a means for connecting the blade to a hub, the flange 10 is turned down in any suitable manner to form an annular ange 18 which is adapted to coact with a similarly formed depression in a hub member in which the blade may be secured.

There has thus been provided by the present invention a novel propeller blade and method ofv constructing the same, whereby the result ant blade is of an entirely seamless and integral construction and exceptionally durable and rugged in operation. During the various novel steps outlined, the grain of the metal has been stretched substantially only in the direction of the` application of the principal stresses and forces encountered durlng operation, thus resulting in a blade offering maximum resistance to the forces tending to disrupt the blade while rotating. In the novel method described herein, the formation of a substantially cylindrical blank having a wedge-sha ed end greatly facilitates the formation o the linished blade as does also the expansion of such blank into a member of substantially elliptical section.

While one series of steps for forming a hollow blade has been illustrated and described, it is to be understood that the invention is not limited thereto. For example, the wall of the blank may be expanded to a section other than elliptical and each section may be greater or less than the correspondin section of the finished blade. It is also to Ee understood that the angular twist may be initiated during the intermediate ste if desired. vVarious other changes may e made in the details of construction and in the method of manufacture without departing from the spirit of the invention as well understood by those skilled in the art. Reference will, therefore, be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. The art of producing a propeller blade which comprises elongating a cupped metal member to form a tube the closed end of which is wedge-shaped, varying the perimetrical dimensions of the tube to correspond with those of the blade to be formed, and pressing the resultant work-piece into the shape to be given the blade.

2. The art of producing a propeller blade which comprises elongatin a cupped metal member to form a tube c osed at one end, varyingthe thickness of the tube circumferlll i metal billet tovform 4 yl`the closed a wedge and section of said lastly vpressures to transform open end towardthe closed end, deforming the end of the tube into the shape of a wedge, expanding the tube to Jr'orm a substantia ly elliptical blank the circumferential dimensions of which correspond with those of the blade to be formed, and ressing the resultant blank into the shape to egiven the finished blade.

seller blade from a seamless hollow cylinrical blank closed at one end including deforming the blank adjacent the closed end into the shape of a wedge, transforming the resultant blank into a paddle, and employing external and internal pressures to deform the paddle into a finished blade having an axial twist and an aerofoil section.

In testimony whereof I have signed this specification.

SPENCER HEATH.

4. The method of lforming a hollow propeller blade which comprises elongating a metal memberv closed at one end to form a cylindrical hollow blank, drawing the end of the blank into the shape of a wedge, expanding the blank by internal `pressure to form a blank having a substantially elliptical section, and employmg external and internal the resultant blank shape desired to be given the nished y5. lThe method of forming a hollow prodrawing. a

peller blade which' comprises a hollow cylindrical tube having al wedge-shaped end, expanding the tube to increase the circumferential dimensions thereof to conform substantially to the circumferential dimensions of the blade to be formed, and employin external and internal pressures t0 trans orm the resultant work-piece into the shape desired to be given the inished blade.

6. The method of forming a hollow metallic propeller blade from a hollow billet closed atone end which includes drawing said billet to form a hollow cylindrical tube, drawing end of said tube into the shape of successively deformin the cross tubeinto first, an e ipseand an aerofoil.

7. The method of producing a hollowl propeler blade gmprisingshaping a cylindri tu e blank having an elliptical cross section and pressing the blank into the shape having an aerofoil section.

8. The method of forming a. propeller blade comprising elongating a cuppedV disk to form a tube, drawing `the closed end of the tube intovthe shape of a wedge, employing internal and external pressures to-transform the tube into a pa forming the paddle into a blade of aerofoil sectionand forming an annular flange on the nouw metal root end of the blade from the metal thereof.

9. The methodof forming a hollow prohaving a-closed wedge-shaped end into a desired, v 

